The present invention is directed a reactor switch.
The invention relates to reactor switches of the type described by G. Koppl and E. Ruoss in the paper "Schaltuberspannungen in Hoch- und Hochstspannungsnetzen" ("Switch-over voltages in high and super-high voltage systems"), published in Brown Boveri Mitt. 1970, p. 554 ff. When the switching point of the prior art reactor switch is opened, an oscillating voltage can occur as a recurring voltage as a result of the inductance and the capacitance of the reactor when the current breaks off and before its natural zero transition. The amplitude of the voltage can be limited by damping resistors placed in parallel with the switching point, if necessary. If during the opening process, the contacts of the switching points separate only shortly before the zero transition of the current, an arc can develop between the switch contacts. If this arc is coupled with a sufficiently high oscillating voltage amplitude, arc oscillations with very rapid voltage changes can additionally occur at the reactor. This poses a risk of damage to the insulation 4' (symbolically illustrated of the reactor 4 (FIG. 1).
The present invention provides a reactor switch of the generic type in which arc-back oscillations with excessively high voltage changes are avoided in a simple and reliable manner.
The reactor switch according to the invention is characterised by the fact that steep slopes of high-frequency arc-back oscillations, possibly occurring at the reactor, are limited with comparatively low energy absorption. Insulation damage at the reactor can thus be avoided even with resistors which are dimensioned only for absorbing small quantities of energy. In addition this switch can be used for carrying out a large number of switching actions within a very short time without problems.
German Offenlegungsschrift No. 3,038,516 teaches to arrange voltage-dependent resistors in parallel with a switching path to provide for optimum switching of transformers. But, another switching path, which has connected in parallel therewith a resistor and an auxiliary switching path, is provided between this switching path and the transformer. However, such an arrangement is rather elaborate since it requires two switching paths with different circuits.
In addition, F. Parschalk, in his paper "Hochstspannungs-Druckluftschnellschalter grosser Ausschaltleistungen fur Schwerpunkte des Verbundbetriebes" ("Super-high voltage compressed-air high-speed switches for large breaking capacities for focal points in the compound-system operation"), BBC-Nachrichten, volume 41 (1959), page 328, describes a switch in which a series circuit of an auxiliary switching chamber and a voltage-dependent resistor is located in parallel with a quenching contact. This resistor is in parallel with the quenching contact only during the very brief breaking process which achieves ideal potential control and thus optimum breaking performance.
Properties and advantages of the invention are explained below in greater detail in relation to non-limiting embodiments which are shown in the drawings.